Au Co is believed to be an immortal mountain fairy, who bore an egg sac that hatched a hundred children known as ancestors of the Vietnamese people. The festival also kicked off a series of spring events in Phu Tho province.

An important worship ceremony of Mother Au Co Temple Festival

The same day, locals and visitors attended the traditional Ploughing Festival to pray for good weather and bumper crops in Doi Son commune in Ha Nam province. The event dates back from 987 when King Le Dai Hanh ploughed the field himself in Doi mountain to promote farming activities and encourage farmers to work harder for bumper crops. Various activities including folk games, ceremonial drum performance, folk singing, and processions, are taking place at the festival.